Canines are used to sniff explosives, weapons and drugs. They're also trained to protect police officers and search for missing people. German shepherds are often used on K9 teams because they're highly trainable and very loyal, according to the American Kennel Club.

Dogs have been pulling sleds for generations. In Alaska, sled dogs have competed in the long-distance Iditarod Trail Sled Dog Race since 1973. Competitors start the race with a team of 16 dogs that pull the sleds about 1,000 miles from Anchorage to Nome.

Some dogs can be trained to help blind and visually-impaired individuals navigate their day-to-day activities. In the United States, guide dogs can accompany individuals into any business or other establishment that the general public can access.

4. Conservation aide

Dogs are being trained and used for environmental protection efforts. Organizations like Working Dogs for Conservation are training canines to identify invasive plants and help with weed eradication projects. Dogs are also trained to identify various types of animal scat that help researchers track animal behavior.

Truffle hunting doesn't just belong to pigs. Dogs are also good at finding the valuable fungi. The Lagotto Romagnolo, an Italian breed, specializes "in truffle-searching on any kind of ground," according to the Lagotto Club of America.